Process for catalytically converting naphtha to light olefins with predominant modes

Abstract

A process for converting naphtha to predominantly ethane comprising contacting a naphtha stream with a zeolitic catalyst comprising a noble metal and hydrogen to produce a light paraffin stream comprising ethane and propane; wherein the catalyst comprises at least about 0.005 wt % noble metal at a ratio of hydrogen to hydrocarbon of less than about 5. In a predominantly propane mode, the catalyst comprises about 0.005 wt % noble metal and operates at a reaction temperature of no more than about 450° C. The process can be switched between modes depending on the desires of the operator.

Claims: 
     
         1 . A process for converting naphtha to predominantly ethane comprising:
 contacting a naphtha stream with a zeolitic catalyst comprising a noble metal and hydrogen to produce a light paraffin stream comprising ethane and propane; wherein the catalyst comprises at least about 0.005 wt % noble metal at a ratio of hydrogen to hydrocarbon of than about 5.   
     
     
         2 . The process of  claim 1  wherein the ratio of hydrogen to hydrocarbon is no more than about 2. 
     
     
         3 . The process of  claim 1  wherein the catalyst comprises less than about 0.5 wt % noble metal. 
     
     
         4 . The process of  claim 1  wherein the catalyst comprises at least about 0.02 wt % noble metal. 
     
     
         5 . The process of  claim 1  wherein the catalyst comprises at least about 0.1 wt % noble metal. 
     
     
         6 . The process of  claim 1  further comprising a reaction temperature of at least 425° C. and a reaction pressure of less than about 20 bars. 
     
     
         7 . The process of  claim 1  further comprising a reaction temperature of at least about 440° C. 
     
     
         8 . The process of  claim 1  wherein the noble metal is platinum. 
     
     
         9 . The process of  claim 1  wherein sulfur is contained in the feed. 
     
     
         10 . A process for converting naphtha predominantly to propane comprising:
 contacting a naphtha stream with a zeolitic catalyst comprising a noble metal and hydrogen to produce a light paraffin stream comprising propane; wherein the catalyst comprises at least about 0.005 wt % noble metal, operating at a reaction temperature of no more than about 440° C.   
     
     
         11 . The process of  claim 10  further comprising a noble metal catalyst concentration of 0.01 to 0.1 wt %. 
     
     
         12 . The process of  claim 10  wherein the ratio of hydrogen to hydrocarbon is less than about 5. 
     
     
         13 . The process of  claim 11  wherein the reaction temperature is no less than about 350° C. 
     
     
         14 . The process of  claim 10  further comprising a reaction pressure of no more than about 20 bars. 
     
     
         15 . The process of  claim 10  further comprising a reaction temperature of no more than about 425° C. 
     
     
         16 . The process of  claim 10  wherein the noble metal is platinum. 
     
     
         17 . A process for converting naphtha to ethane and propane comprising:
 contacting a naphtha stream with a zeolitic catalyst comprising a noble metal and hydrogen to produce a light paraffin stream comprising ethane and propane; wherein the catalyst comprises at least about 0.005 wt % noble metal;   switching from a predominant ethane mode at a ratio of hydrogen to hydrocarbon of less than about 2 to a predominant propane mode at a ratio of hydrogen to hydrocarbon of at least about 2; or   switching from a predominant propane mode at a reaction temperature of no more than about 440° C. to a predominant ethane mode at a reaction temperature of more than about 440° C.   
     
     
         18 . The process of  claim 17  wherein the catalyst comprises about 0.01 to about 0.2 wt % noble metal. 
     
     
         19 . The process of  claim 17  further comprising increasing the ratio of hydrogen to hydrocarbon to at least 2.5 when switching from predominant ethane mode to predominant propane mode. 
     
     
         20 . The process of  claim 17  further comprising unloading a catalyst with less than 0.1 wt % noble metal and loading a catalyst with at least 0.1 wt % noble metal when switching from a predominant propane mode to a predominant ethane mode or unloading a catalyst with at least 0.1 wt % noble metal and loading a catalyst with less than 0.1 wt % noble metal when switching from a predominant ethane mode to a predominant propane mode. 
     
     
         21 . A process for converting naphtha to ethane and propane comprising contacting a naphtha stream with a catalyst comprising a noble metal and hydrogen to produce a light paraffin stream comprising ethane and propane, wherein the catalyst comprises at least about 0.1 wt % noble metal; switching from a predominant ethane mode at WHSV of less than 4 hr −1  to a predominant propane mode at WHSV of at least 4 hr −1 ; or switching from a predominant propane mode at WHSV of at least 4 hr −1  to a predominant ethane mode at WHSV of less than 4 hr −1 .